For calibrating measuring devices, such as vector network analyzers, high accuracy phase reference signals are employed. Such signals are, for example, generated by comb generators. A comb signal is a signal consisting of a number of discrete frequency pulses that are arranged in an equidistant manner in the frequency domain.
By generating a comb signal and supplying it to a measuring port of a vector network analyzer, the phase response of the vector network analyzer over the frequency can be determined and calibrated. This is for example shown in the patent document U.S. Pat. No. 8,508,241B2.
Conventionally, comb signals are generated using step-recovery-diodes. This type of signal generation though is disadvantageous, since the number of frequency pulses is limited. Also, most of the signal power is in the low-frequency area of the generated comb signal, resulting in very low power high frequency pulses.
Accordingly, there is a need for a comb signal generator, and a measuring device employing such a comb signal generator, which allow for a high number of selectively spaced frequency pulses with a high power.